The present invention relates generally to controlling data arrangement in a storage server which provides storage area used by a service server.
In recent years, non-volatile memories (NVM) such as Flash memory are used in various types of electronic equipment. Unlike a hard disk drive (HDD), the nonvolatile memory does not involve a mechanical operation, and permits faster access than the HDD.
Nonvolatile memories are also used in enterprise applications such as a server and a storage system that need fast data access. Particularly, nonvolatile memories mountable in servers become inexpensive, and are thus becoming popular.
A well-known conventional technique includes a system in which Flash memory is used as data cache memory but not as a main memory (see, for example, the description of US 2009/0024793 A1). In such system, the cache driver included in an OS, or the like, running on a server stores some cache data in the Flash memory and discharges other cache data from the Flash memory based on the access characteristics of data (e.g., access frequency). By doing so high speed data access is achieved.
Also, another well-known conventional technique includes a storage system in which a storage medium having a higher access capability and a storage medium having a lower access capability configure a tiered storage area whereby, based on the access characteristic of data, the storage area for the data is changed (see, for example, the description of JP Laid-open Patent Publication No. 2000-293317).